Researchers conducted six studies to investigate how best to challenge science deniers

When responding to science denialism (or, for that matter, any sort of false or harmful information), such as claims that vaccines are ineffective and harmful, it can be difficult to establish the right strategy. Because of the fast-paced way in which information spreads these days, there is a risk that responding to a given inaccurate claim can give it further oxygen, leading the falsehood to reach more people who are vulnerable to being misled, and so forth. There's also the possibility of the "backfire effect" – people who already endorse the false claims reacting to the debunking information by digging into their beliefs further (though there's now evidence such fears were overhyped, and that the backfire effect may not be a regular occurrence overall).

To better understand when science-denialism debunking does and doesn't work, Philipp Schmid and Cornelia Betsch, both of the University of Erfurt in Germany, ran a series of studies that involved online respondents being exposed to various sorts of science debates. The results, published in Nature Human Behavior, offer some useful insights about how to best stem the tide of science denialism.

As the authors explain, there are two primary tactics used to rebut science denialism (and to argue in general): "An advocate can aim to overwhelm the opposing position by providing support only for her own view or she can aim to refute the opposing position by attacking its plausibility and explaining why it is wrong." This is called a topic rebuttal. The other tactic is known as a technique rebuttal: The debunker can highlight the common techniques used by science deniers and show how a given argument fits in. For example, the claim that vaccines aren't 100 per cent safe reflects a so-called "impossible expectation", since no medical procedure is 100 per cent safe.

The researchers ran six online experiments on almost 1,200 participants dealing with vaccines and climate change, in which they gauged success based on participants' behavioural intentions and attitudes (either getting vaccinated or taking action to fight climate change, depending on the study, and attitudes towards those activities) before and after listening to, or reading a debate with, a science denier. Participants were randomly assigned to conditions where a science advocate was or wasn't present to respond to the misinformation, and where the advocate used topic rebuttals, technique rebuttals, or both.

Most importantly, "The results show that public discussions with a science denier have a damaging effect on the audience, as revealed by negative changes in attitudes and intentions [toward vaccination/ tackling climate change]." This negative effect was still present, though it was mitigated, even when a debunking advocate was absent. The researchers' advice based on this rather disheartening outcome was that "advocates who take part in debates should not expect too much for their efforts — but that it's still important to at least rebut science denialists when they show up or write in public forums.

Topic and technique rebuttals had the same mitigating effect and there was no evidence that using a combination of the two provided any additive benefit. On a positive note, the researchers found no significant evidence of a backfire effect in this context.

There are some important caveats here: This is an online study that didn't track real-world behaviour, but rather self-reported attitudes and behavioural intent. As the authors themselves note, longitudinal studies looking at actual behaviour would be useful. But society is early on in understanding, in a scientific way, how persuasion works in this sort of context, and an investigation like this provides some firm early building blocks. Perhaps most importantly, it provides solid evidence that, from the point of view of concerned science advocates, if the choice is to show up to a debate with a science denialist or stay home, showing up is likely the better course of action – the only exception being if the advocate has the power to prevent the debate from occurring at all by abstaining.

But overall, people should temper their expectations about the efficacy of this sort of debunking: the authors argue that "facing deniers in public debates can be only one building block in the concerted effort to fight misinformation. Other recent approaches try to fight misinformation by pre-emptively providing laypeople with the ability to identify false information themselves." At the risk of slipping into cliches about teaching a man to fish, it does feel like early, robust education on critical thinking and evaluating evidence could be more effective than trying to dislodge false beliefs one by one later on in life.

Further reading

—Effective strategies for rebutting science denialism in public discussions

About the author

Jesse Singal (@JesseSingal) is a contributing writer at BPS Research Digest and New York Magazine, and he publishes his own newsletter featuring behavioral-science-talk. He is also working on a book about why shoddy behavioral-science claims sometimes go viral for Farrar, Straus and Giroux.